1. Field of the Invention
This invention relates to an apparatus for swaging a fastener collar onto a fastener pin extending through a pair of facially-engaged workpieces.
2. Description of Prior Developments
Fasteners of the pin and collar type are often used in aircraft construction, e.g. frames and panels used to form aircraft wings and aircraft cabins. In each case a headed fastener pin extends through aligned circular holes in the workpieces being secured together. A fastener collar is fitted loosely on a projecting portion of the pin, after which a fluid-actuated tool is operated to swage the collar radially into circumferential grooves in the pin side surface. The collar is thus firmly secured to the pin. This achieves a high strength fastening action on the associated workpieces which are sandwiched between the collar and the head of the pin.
In some instances the workpieces have overhanging wall sections or flanges that limit access of the nose assembly of a fastener tool to the pin and collar assembly. One particular instance of such a limited access situation is an upright frame structure used to mount or frame windows in aircraft cabins. The upright window frame structure includes a relatively small, substantially annular frame element nested within a larger frame element. These frame elements are held together by a series of spaced apart pin and collar fasteners.
The larger frame element has a channel-shaped cross section oriented so that the bottom web of the channel forms the outer edge surface of the frame, and the side flanges of the channel extend radially inwardly from the web to define the two flat upright major faces of the frame. The smaller frame element has a channel-shaped cross section sized to fit into the larger channel. The two channel members are secured together by several swaged pin and collar fasteners extending through the mating channel walls at spaced points. The channel flanges have different orientations at different points around the frame structure, e.g. horizontal orientations at the upper and lower edges of the right structure, and vertical orientations along the side edges of the ring structure.
In this application the swaging nose assembly of the installation tool for the fasteners has to fit into the limited space between the flanges of the smaller channel in order to effectively grip the pin and swage the fastener collar. Because of the limited space, prior nose assemblies have been difficult to position and manipulate within such confined and obstructed application areas. U.S. Pat. No. 4,598,572 and U.S. Pat. No. 4,796,455 show apparatus for a generally similar purpose.